//! Command-line argument resolution.

use std::path::Path;

/// Resolves the CLI arg to a concrete script file. Accepts any of:

/// - path to a `.lua` file

/// - path to a directory containing `main.lua`

/// - path without extension that has a sibling `.lua` file

///

/// Errors with a helpful message if none match.

pub fn resolve_script_path(arg: &str) -> Result<String, String> {

let path = Path::new(arg);

if path.is_dir() {

let main = path.join("main.lua");

if main.exists() {

return main

.to_str()

.map(String::from)

.ok_or_else(|| format!("non-utf8 path: {}", main.display()));

}

return Err(format!(

"no main.lua found in directory '{}'. Create a main.lua there, or pass a .lua file directly.",

path.display()

));

}

if path.is_file() {

return Ok(arg.to_string());

}

let with_lua = path.with_extension("lua");

if with_lua.is_file() {

return with_lua

.to_str()

.map(String::from)

.ok_or_else(|| format!("non-utf8 path: {}", with_lua.display()));

}

Err(format!(

"script not found: '{}'. Pass a .lua file, a directory with main.lua, or a name with a sibling .lua.",

arg

))

}

#[cfg(test)]

mod tests {

use super::*;

use std::fs;

use tempfile::TempDir;

#[test]

fn resolves_direct_lua_file() {

let dir = TempDir::new().unwrap();

let file = dir.path().join("game.lua");

fs::write(&file, "-- test").unwrap();

let arg = file.to_str().unwrap();

assert_eq!(resolve_script_path(arg).unwrap(), arg);

}

#[test]

fn resolves_dir_with_main_lua() {

let dir = TempDir::new().unwrap();

let main = dir.path().join("main.lua");

fs::write(&main, "-- test").unwrap();

let resolved = resolve_script_path(dir.path().to_str().unwrap()).unwrap();

assert_eq!(resolved, main.to_str().unwrap());

}

#[test]

fn errors_for_dir_without_main_lua() {

let dir = TempDir::new().unwrap();

let err = resolve_script_path(dir.path().to_str().unwrap()).unwrap_err();

assert!(err.contains("no main.lua"), "got: {err}");

}

#[test]

fn errors_for_missing_path() {

let err = resolve_script_path("/definitely/not/a/real/path/xyzzy").unwrap_err();

assert!(err.contains("not found"), "got: {err}");

}

#[test]

fn adds_lua_extension_when_missing() {

let dir = TempDir::new().unwrap();

let file = dir.path().join("foo.lua");

fs::write(&file, "-- test").unwrap();

let bare = dir.path().join("foo");

let resolved = resolve_script_path(bare.to_str().unwrap()).unwrap();

assert_eq!(resolved, file.to_str().unwrap());

}

#[test]

fn dir_takes_precedence_over_sibling_lua() {

// If `foo/` exists as a dir with main.lua AND `foo.lua` exists, the

// dir should win because is_dir() is checked first.

let dir = TempDir::new().unwrap();

let subdir = dir.path().join("foo");

fs::create_dir(&subdir).unwrap();

let main = subdir.join("main.lua");

fs::write(&main, "-- dir").unwrap();

let sibling = dir.path().join("foo.lua");

fs::write(&sibling, "-- sibling").unwrap();

let resolved = resolve_script_path(subdir.to_str().unwrap()).unwrap();

assert_eq!(resolved, main.to_str().unwrap());

}

}